1. Technical Field
The present invention relates to a power supply device which can supply an electric power to an electric load even if power supply is stopped from a commercial power source.
2. Description of Related Art
As a backup power source during a power failure, a secondary battery such as a lead storage battery has been used. In addition, Japanese Unexamined Patent Application Publication No. 2007-189813 discloses the backup power source which supplies a receiver with the sum of electrical energies from at least two or more dry-cell battery systems when a commercial power source is not available.